1. Field of the Invention
For effectively reducing shift shocks caused when starting an automotive vehicle, it is known to automatically shift an automatic transmission to a third speed gear after it has been changed to a forward drive range from a neutral range so as to start the vehicle moving. The automatic transmission is then shifted to a first speed gear after the speed of rotation of a turbine of the torque convertor drops and reaches a critical speed of rotation, which has been predetermined. Such an automatic transmission is known from, for instance, Japanese Unexamined Patent Publication No. 61-65,949.
2. Description of Related Art
An automatic transmission of this type tends to be shifted to the first speed gear, without passing the third speed gear, when it is shifted to the forward drive range from a reverse range while passing through the neutral range on starting of the car. This is because the torque convertor holds the speed of rotation of the turbine (which is referred to as the turbine speed, for simplicity) at zero (0) while the automatic transmission is manually changed into the reverse range from a park range. Although an increase in turbine speed is caused while the automatic transmission is in the neutral range, the turbine speed is still lower than the critical speed when the automatic transmission is manually changed into a forward drive range. Accordingly, the automatic transmission may accidentally be shifted directly into the first speed gear without temporarily shifting into the third speed gear. Some drivers prefer to shift the automatic transmission to the neutral range at certain times, such as immediately after the car is brought to a stop at a traffic light. A shift to a forward drive range then is made when the car is to move again. When repeatedly changing into the forward drive range in a short period of time, the known automatic transmission referred to above may be automatically shifted into the third speed gear before it shifts into the first speed gear, suitable for acceleration, whenever the vehicle is started. This leads to adverse effects on the starting performance of the vehicle.